Alzheimer's and Parkinson's: what are the similarities and differences?

Alzheimer's disease besides Parkinson's disease are brain illnesses that get worse over time because brain cells slowly break down. Both illnesses sometimes lead to dementia - yet the first problems that show up and the way the illness moves forward are not the same.

Parkinson's disease starts as a problem with body movement. It usually shows up after a person turns 60 - yet it sometimes starts earlier. The clearest signs are a hand or arm that shakes while at rest, slow steps, stiff arms or legs and a tendency to fall. As years pass, the person often forgets things, feels sad, has hard stools, sees things that are not there and shows sudden mood swings. Doctors divide the illness into five steps - step one has mild signs on one side of the body - step five leaves the person bed-bound and fully dependent on others. Symptoms rise and fall during the day and each patient moves through the steps at a different speed.

Treatment for Parkinson's aims only to ease the problems that appear. Drugs adjust the level of brain chemicals to calm stiff muscles, shakes, sadness or constipation. A surgeon can place wires deep in the brain to reduce shakes and a physiotherapist teaches exercises that keep the patient walking and dressing alone. No drug or operation stops the illness from advancing.

Alzheimer's disease attacks memory, good sense and mood. It usually starts after age 70 - yet it sometimes begins earlier. The patient forgets recent events, loses track of time, grows irritable, suspects loved ones of theft, stops bathing and sleeps for long hours. The illness moves through seven steps - step one shows no outward change - step seven ends with the patient unable to swallow or move. Each step brings a clear loss of ability.

Drugs such as donepezil, galantamine and memantine give a few extra months of clearer thought - yet they do not cure the illness or bring back lost skills. Other drugs calm night time fear or shouting - yet they do not slow the disease itself.

When the two illnesses are set side by side, Alzheimer's dementia is deeper and robs the person of daily skills for a longer stretch. Parkinson's dementia moves faster - yet the patient's abilities shift from hour to hour. Both illnesses later bring dark moods, worry, visions of people or animals that are not present and sudden tears or anger.

Daily life with either illness demands outside help. A nurse who visits the home, a therapist who guides safe exercises and a support group for families lift part of the load and add comfort. The two illnesses share a few features - yet they remain separate diseases. No single gene causes either one and a person can have one illness without the other.